feat(01-01): create Zustand store with 6 slices, IPC batcher, and unit tests

- Install zustand 5.x and immer 11.x dependencies
- Create 6 Zustand slices: navigation, company, selection, ui, communication, social
- Create combined store with devtools + immer middleware
- Create IPC event batcher with 50ms debounce window (schedule/flush/dispose)
- Create typed selector hooks for narrow state subscriptions
- Add 14 unit tests covering store initialization, slice behaviors, and batcher timing

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/unit/ipc-batcher.test.ts

@@ -0,0 +1,73 @@
+import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
+import { createEventBatcher } from "@renderer/lib/ipc-batcher";
+
+describe("createEventBatcher", () => {
+  beforeEach(() => {
+    vi.useFakeTimers();
+  });
+
+  afterEach(() => {
+    vi.useRealTimers();
+  });
+
+  it("calls callback after windowMs timeout (50ms)", () => {
+    const callback = vi.fn();
+    const batcher = createEventBatcher(callback, 50);
+
+    batcher.schedule();
+    expect(callback).not.toHaveBeenCalled();
+
+    vi.advanceTimersByTime(50);
+    expect(callback).toHaveBeenCalledTimes(1);
+  });
+
+  it("coalesces multiple schedule() calls within window into single callback", () => {
+    const callback = vi.fn();
+    const batcher = createEventBatcher(callback, 50);
+
+    batcher.schedule();
+    batcher.schedule();
+    batcher.schedule();
+
+    vi.advanceTimersByTime(50);
+    expect(callback).toHaveBeenCalledTimes(1);
+  });
+
+  it("flush() immediately invokes callback and clears pending timer", () => {
+    const callback = vi.fn();
+    const batcher = createEventBatcher(callback, 50);
+
+    batcher.schedule();
+    batcher.flush();
+
+    expect(callback).toHaveBeenCalledTimes(1);
+
+    // Advancing time should not trigger another callback
+    vi.advanceTimersByTime(100);
+    expect(callback).toHaveBeenCalledTimes(1);
+  });
+
+  it("dispose() cancels pending timer without invoking callback", () => {
+    const callback = vi.fn();
+    const batcher = createEventBatcher(callback, 50);
+
+    batcher.schedule();
+    batcher.dispose();
+
+    vi.advanceTimersByTime(100);
+    expect(callback).not.toHaveBeenCalled();
+  });
+
+  it("schedule() after flush() starts new timer", () => {
+    const callback = vi.fn();
+    const batcher = createEventBatcher(callback, 50);
+
+    batcher.schedule();
+    batcher.flush();
+    expect(callback).toHaveBeenCalledTimes(1);
+
+    batcher.schedule();
+    vi.advanceTimersByTime(50);
+    expect(callback).toHaveBeenCalledTimes(2);
+  });
+});